From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4D4E53A5438; Thu, 6 Aug 2026 19:03:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786043019; cv=none; b=NFyh4uRmTUtyCsZeW/RNSgjV+MEuyGa/XTpXhIQpKxXmII7ASIi1OKzb2S6JdmXXmeFFjgVqyaNhJ5/InxeMgVVpQkyS5UCwla0z5AE4upYAvvClrQIHfWrwNBZtGPzjtwYW0ZGKYSkHOrbumSuqvDpur8N9ru3LrrWayGaXZbM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786043019; c=relaxed/simple; bh=rWIN3CAoTOmn/dHplE3EM/vqreNCuPNk0XcMox2UW4M=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=EYAtHGbMJFBLVATPNzfvFcaEiXwKeRfSBPR80eomPV90E+ZQDK1V4DDCI5DkqrV6mUMy7x9dyJ/3aAny/FFTnr0wb7MqJtg3zfVgR/vqHAFjyhqtI1Q2j353loKTRRmXGXQI+DTUTQui7Q+flU+1K1OKGl++pfoHOhTG4D1gg+0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=S6HabWo4; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="S6HabWo4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 869D21F000E9; Thu, 6 Aug 2026 19:03:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1786043017; bh=dRt0s7vfM2bnz3NqZRZ9IExdeacv27vJYYUrCTtxIiI=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=S6HabWo4OztTo/PiObEDh6luKFIDnwMqPcGG/RkJg9S5pUwEXj8utnavmqMb/S1+t YdwJzCVygJOtG352PEat3qf+0bzmGKHiWhmRT1DC19OPC6j8ZyjN9m3mXkBKdw0Cxn Kwru4dhgGBMyzpD3DN/wJTzu2U6z1fu54kScQfIA= Date: Thu, 6 Aug 2026 12:03:37 -0700 From: Andrew Morton To: "David Hildenbrand (Arm)" Cc: Hugh Dickins , Jason Gunthorpe , John Hubbard , Peter Xu , Kiryl Shutsemau , Ackerley Tng , Frank van der Linden , linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] mm/gup: fix always draining LRU caches in collect_longterm_unpinnable_folios() Message-Id: <20260806120337.2c7d65fd7f9d534bf4ffed1b@linux-foundation.org> In-Reply-To: <564e64b2-1b71-4d8e-a29e-dc98e8deb006@kernel.org> References: <20260731-check_and_migrate_movable_folios-v1-1-e0002d7b791e@kernel.org> <20260801122040.7230a8eb0dc846ce357fba67@linux-foundation.org> <564e64b2-1b71-4d8e-a29e-dc98e8deb006@kernel.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 6 Aug 2026 18:29:39 +0200 "David Hildenbrand (Arm)" wrote: > On 8/1/26 21:20, Andrew Morton wrote: > > On Sat, 1 Aug 2026 11:49:39 -0700 (PDT) Hugh Dickins wrote: > > > >>> Found by code inspection. If someone has a testcase that can easily > >>> trigger this and result in migration problems, please test! But this > >>> change seems to be "obvious the right thing to do". > >> > >> Sorry, I don't (as perhaps is too obvious). And I'm a wee bit afraid > >> that some of the problems which those changes happened to succeed in > >> fixing, might now reappear once the drains are finely targeted. > >> > >> Am I arguing for a delay before advancing to stable? Perhaps, but > >> I think not: it's probably best to get that working as intended, > >> then deal with any fallout if it arises: just be on guard. > > > > This patch is in mm-new, so it's still some months away from -stable > > eligibility. > > I hope you meant weeks :) I was unclear. The patch is (now) in mm-unstable, aimed at 7.3-rc1. But I don't expect it to be released in -stable kernels for some time after we've added it to 7.3-rc1. I don't know what the latency is, really. Seems to take a week or three for Greg to grab these things, but how much longer it takes for it to get into the 7.2.x and earlier kernels is probably quite variable. > Can we get that into 7.3-rc1, though? There is quite the overlap with > guest_memfd work, and I'll send another patch that depends on this. Yep. In the second-week-of-merge-window batch.